Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 48: Poster 2

HL 48.55: Poster

Donnerstag, 26. März 2009, 15:00–17:30, P2

The impact of strain waves travelling across a quantum dot on the optical response of the dot — •Jan Huneke¹, Vollrath Martin Axt², and Tilmann Kuhn¹ — ¹Institut für Festkörpertheorie, Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster — ²Institut für Theoretische Physik III, Universität Bayreuth, 95440 Bayreuth

We analyze the influence of phonon wave packets travelling across a semiconductor quantum dot on the optical response resulting from the lowest dot transition. For this purpose we compare two different structures: (i) a phonon wave packet is generated by the optical excitation of a single quantum dot near a surface, which after reflection at the surface reenters the dot; (ii) a phonon wave packet is generated by the excitation of a nearby second dot and then travels across the quantum dot.Our theoretical model includes pure dephasing interactions between electronic and phononic degrees of freedom in quantum dot systems that are driven by ultrafast laserpulses. We discuss the linear response as well as pump-probe and four-wave-mixing signals for both situations. It is shown that the phonon wave packets leave a distinct signature which allows their detection in time-integrated as well as time-resolved regimes. We study the dependence of the signals on the origin of the phonon wave packets and find, although the strain fields are very similar, clear differences in the optical response allowing for a distinction between wave packets of different origins.